Sinks not draining/poor venting?

[buckarooman]

Two new under sink vents and it still is not draining my sinks, if I unscrew the air vent the sinks will suck down like a champ. I can't have a roof vent because I have a island sink, the only roof vent I've got is for the bathroom gray water tank and the black water tank, and there is only one vent but I don't have issues with the bathroom tank or the black tank. I'm at a loss, either my tank just is vented poorly and it's what I get to live with.

[buckarooman]

My wife has small hands wonder how she would take it to sticking a arm in there and cutting the pipe off the bottom of the tank, or I'm going to the part store and buying a gas can vent the little yellow kind, you drill and add it to the tank.

[wvcampers]

You could try to pull the pipe up from the top. If you pull it all of the way out you may not be able to get back in. You could cut the floor under the sink cabinet and possibly see the top of the tank. The pipe may go straight into the tank and it may not. If you can get access to the tank from under the floor you can possibly see the drain going into it.

[cbshoestring]

I found a similar complaint on a DIY website. I did NOT read all 5 pages to find a solution for you...but I will provide a LINK :B

[garyp4951]

That tank is going to have to be vented somehow, maybe out of the top to the other tank top.

[buckarooman]

wvcampers wrote:
The vent under the sink will work as long as the drain is not under pressure. You could try filling the sink until it won't drain. then carefully loosen the auto vent or use a screwdriver to release the seal and see if the sink will drain and if it is sucking air or discharging air. If I am right about the pipe being in the tank too far it will be discharging air because there will be pressure on the tank.

There's definitely pressure that's how I I get it to drain normally, if you unscrew it it let's a big burp of air out. With that said how do fix that? Drop the tank and cut the pipe? Pull up on the pipe?

[wvcampers]

The vent under the sink will work as long as the drain is not under pressure. You could try filling the sink until it won't drain. then carefully loosen the auto vent or use a screwdriver to release the seal and see if the sink will drain and if it is sucking air or discharging air. If I am right about the pipe being in the tank too far it will be discharging air because there will be pressure on the tank.

[buckarooman]

What a pain in the butt for a rv to not do it right the first time.

[wvcampers]

The hose connecting the tanks will work in theory. The problem will be when the hose becomes full of liquid you have lost your vent again. Any vent must come off of the top of the tank. When plumbing a house the vents from the first floor must go above the highest fixture on the second floor before being tied together, or it must go through the roof separatly. If the first floor vent is connected to the second floor drain then it becomes a drain and not a vent. A multi floor building will have a designated vent stack which no drains run into. Best bet is to drop the tank.

[Timay]

Yeah, he is talking about the SINK draining if the valve is open, NOT the tank. You kinda got stuck on the TANK draining.

Tim

[buckarooman]

buckarooman wrote:

Old-Biscuit wrote:
If you drain galley tank and leave drain valve OPEN does kitchen sink drain ?

Which Air Admittance Valves are you using......cheap $5-$6 black ones from Home Depot/Lowes?

The tank will drain great when it's drain valve is opened, I need to change out the gate valve as it has a drip. The admittance valve I've used was one from Home Depot first, then camping it did it again so I ran down to a rv parts store and got one from there. Is there a better type of valve?

I already replied about that sorry for the miss communication

[Old-Biscuit]

I will ask this just one more time and then I am moving on...........


"If you drain galley tank and leave drain valve OPEN does kitchen sink drain"?

[buckarooman]

So here's my thinking, what if I built a short chunk of hose to hook to both drain outlets under the trailer, and kept them level and elevated. Tying the two tanks together one being roof vented one not wouldn't the one that's not beneifet from the one that is?then when I'm ready to leave shut both gates drain what waters left in the hose, or I could put a Y in the middle to be able to drain both tanks at once in the camp ground.

[Rvpapa]

The tank will drain great when it's drain valve is opened, I need to change out the gate valve as it has a drip. The admittance valve I've used was one from Home Depot first, then camping it did it again so I ran down to a rv parts store and got one from there. Is there a better type of valve?
Since no one is telling you GOOGLE "Oatey"
Art.

[Old-Biscuit]

buckarooman wrote:

Old-Biscuit wrote:
If you drain galley tank and leave drain valve OPEN does kitchen sink drain ?

Which Air Admittance Valves are you using......cheap $5-$6 black ones from Home Depot/Lowes?

The tank will drain great when it's drain valve is opened, I need to change out the gate valve as it has a drip. The admittance valve I've used was one from Home Depot first, then camping it did it again so I ran down to a rv parts store and got one from there. Is there a better type of valve?

The TANK drains OK when drain valve is open

BUT.......does the KITCHEN SINK drain better when tank drain valve is LEFT OPEN?

(Tank draining OK suggest the air admittance valve is working --- opening----and providing venting for tank draining)

[buckarooman]

wvcampers wrote:
It is possible that your drain line is into the tank too far. When it becomes under water then it would have to put pressure on the tank to drain. This can happen because you are using the drain line for the vent line. If there were a separate line for the vent it could always allow air out of the tank. Draining into a tank is not like draining into an open ended line. The tank that has the outlet closed needs to allow air out, the opened tank needs to allow air in. The automatic vent will only allow air in.

I wish I didn't have a island sink haha, so are there other valves a guy could use?